As you may already realize, sail performance will suffer as more of the
genoa is rolled up on the furler. You shouldn't consider a furler as a
reefing system rather a convenient way to reduce sail occasionally and to
store the sail when the day is done or the wind really gets to blowing.

Your sail maker can help you with the shape and foam luff if you think you
are going to sail frequently with it partially furled.

Sailing with it partially furled can also change the shape of the sail if
done frequently.

You may not be able to do this because of your limited sail storage
capacity, but I have three head sails, 100% (working high cut), 120 and 150.
Plus I have a staysail (with reef points). My Harken 2.5 is very easy to
change head sails on when I use a pre-feeder. I'm not suggesting that
changing sails is easy during a blow, but it's not a big deal to select a
comfortable size if I am singlehanding or if I know what weather I will
experience during the days sail.

If you are just switching from hanks to furler, you must realize that your
furler sails will be shorter on the luff, due to the drum and the head
swivel. On a boat your size, that might be at least 1-2 ft less than a
hanked on sail.

If you end up with a sail that is still short on the luff, it would be
customary to have a pennant on the head to get the swivel up to near full
hoist. This prevents from halyard wrapping around the furler (better lead to
the halyard sheave). To adjust the luff hoist up and down would require that
you lower the sail to change this pennant or risk a halyard wrap.


--
My opinion and experience. FWIW

Steve
s/v Good Intentions